Removal of primary alkyl halide from hydrocarbons in gasoline boiling range



Sept. 28, 1954 REMOVAL OF T. HORECZY El AL PRIMARY ALKYL. HALIDE FROMHYDROCARBONS IN GASOLINE BOILING RANGE Filed May 19, 1951 ,Bauxite is;I6

Vaporizer I2 Condenser Fresh Hydrocarbons Caustic Solution contaminatedwith Primary AlkyI-Chloride 20 22 Product Free L? From Alkyl- ChlorideHydrolyzer 2 1 Spent Caustic Solution INVENTOR.

Joseph T. Horecgy, Harry.G- Boynton,

ATTORNEY.

Patented Sept. 28, 1954 REMOVAL OF PRIIWARY ALKYL HALHJE FROMHYDROCARBONS IN GASOLINE BOILING RANGE Joseph T. Horeczy and Harry G.Boynton,

town,

Bay-

Tex., assignors, by mesne assignments, to

Standard Oil Development Company, Elizabeth, N. J a corporation ofDelaware Application May 19, 1951, Serial No. 227,266

This application is directed to a method for removing primary alkylchloride from a hydrocarbon fraction.

It is sometimes desirable or necessary to remove alkyl chloride orchlorides from a hydrocarbon fraction containing the same. Examples ofhydrocarbon fractions contaminated by alkyl chloride or chlorides arethe fractions obtained when isoparaffin is alkylated with a low boilingolefin and an active chloride is used as the catalyst. These fractionsboil in the gasoline boiling range and are commonly used for gasolinesand when so used the alkyl chloride contaminant is considered quitedetrimental. It is desirable or necessary to reduce the alkyl chloridecontent of the mixture and this cannot be done by distillation becausethe alkyl chloride contaminants boil in the same range as thehydrocarbons.

The process of the present application involves a combination of stepswhich reduces substantially the amount of alkyl chloride contaminant inhydrocarbon mixtures, such as those obtained by the alkylation ofisoparaffin with a low boiling olefin when using an active chloride asthe catalyst. The process involves the steps of bringing a vaporizedmixture consisting of hydrocarbons in the gasoline boiling range andcontaminated by a small amount of alkyl chloride or chlorides intocontact with bauxite and removing the mixture from contact with thebauxite, condensing it and subjecting the condensed liquid tohydrolysis. A hydrocarbon fraction is removed from the hydrolysis stepwhich is substantially free from alkyl chlorides and is a desirablecomponent for inclusion in gasolines.

By way of explanation of the satisfactory results obtained, we havediscovered that the alkyl chloride in admixture with the hydrocarbons,which are obtained by the alkylation of isoparafiin with a low boilingolefin when using active chloride catalyst, is primary alkyl chloride.When such a contaminated hydrocarbon is vaporized and contacted withfresh bauxite, substantially all of the alkyl chloride is removed fromthe hydrocarbons by catalytic dehydrohalogenation, but as the bauxiteages in use,-the efiiuent contains hydrocarbons contaminated bysecondary and tertiary alkyl chlorides which are considerably moredetrimental to the quality (leaded octane number) of gasoline than theprimary alkyl chloride in the feed stock, but unlike the primary alkylchloride may be readily removed from the hydrocarbons by hydrolysis.Thus, the method of the present invention involves the substantialremoval of alkyl chloride 3 Claims. (Cl. 260-676) contaminants fromhydrocarbons in the same boiling range by a two-step process which doesnot require the frequent regeneration of the bauxite which is used inthe first step of said process.

In conducting our process the feed stock contaminated with the primaryalkyl chloride or chlorides is vaporized and the vaporized mixture iscontacted with bauxite. It is preferred to carry out the contacting stepat a temperature within the range of 500 to 900 F. with a. contact timeof .01 to 1 second. The bauxite may remain on stream for as long as 24hours without regeneration and satisfactory results obtained. It may benoted that when the bauxite has been freshly regenerated it apparentlyacts as a dehydrohalogenation catalyst, so that the effluent removedtherefrom is substantially free from alkyl chloride for the first 6 to 8hours the bauxite is in service and usually is given no furthertreatment. Thus, generally, a bauxite bed which has been in service as acatalyst for from 8 to 24 hours after its last regeneration is thecontacting material used in the first step of our process.

The hydrocarbon product removed from contact with the bauxite and whichis contaminated with secondary and tertiary alkyl chlorides ishydrolized in the presence of an aqueous caustic solution. Thehydrolysis step may be carried out at temperatures within the range of180 to 500 F. If the lower temperatures within the range given are used,it is necessary that a considerable time of contact be used. Hence, forcommercial purposes it is usually desirable to hydrolize under pressureat a temperature between 290 and 500 F. for a contact time within therange of 3 to 5 minutes.

After the bauxite used in the first step of our process has been onstream a considerable length. of time, the chloride content of theeffluent b comes so greatthat it is desirable to regenerate it. Thelength of time the bauxite bed may remain on stream may be varied at theoption of the operator. However, for commercial purposes it will usuallybe desirable to regenerate the bauxite bed after it has been on stream24 or 30 hours. As explained heretofore, the fresh bauxite removessubstantially all of the alkyl chlorides from the gasoline by catalyticdehydrohalogenation so that usually the process of the present inventionis not carried out with a freshly regenerated bed of bauxite. Forpractical purposes, a bauxite bed which has been on stream a minimum of6 to 8 hours, and a maximum of 24 to 30 hours is used in the first stepof our process. The method for regenerating a bed of bauxite is wellknown to the art. By way of example, the bauxite bed may be regeneratedby passing steam through it at a temperature in the range of 500 to 900F. for no less than 30 minutes.

The method for carrying out the present invention will be described ingreater detail in conjunction with the drawing in which the figure is inthe form of a flow sheet illustrating a mode for practicing theinvention.

Turning now specifically to the drawing, feed stock consisting ofhydrocarbons in the gasoline boiling range which is contaminated by asmall amount of primary allryl chloride or chlorides in the same boilingrange is passed through inlet line H to vaporizer i2 where the mixtureis vaporized and is withdrawn through line It and sent to chamber itcontaining a bed of bauxite E5. As heretofore explained the bauxite usedis generally on stream for the time interval of 6 or 8 hours to 24 hoursafter its last regeneration. The eiiiuent from chamber I is withdrawnthrough line it and passed through condenser il where it is liquefiedand the liquid is withdrawn through line i8 and passed to hydrolyzer l0.Aqueous caustic solution is introduced to the hydrolyzer throu h inletline 20 and spent aqueous solution is withdrawn through outlet ii. Adesired product having a suiilciently low alliyl chloride content tomake it suitable for inclusion in gasoline is withdrawn through outletline 22.

The invention will be further described by the following example:

Example I The (37+ bottoms resulting from the distillation of thealkylate, product resulting from the alkylation of isobutane withethylene was contaminated with primary chlorides reported upon analysisat weight per cent Cl. This mixture was vaporized and contacted with abed of ite at a reactor temperature of 700 F. at a pressure of 70 p. s.g. with a contact time of 0.1 second. The efiluent was condensed. Asample withdrawn after the bauxite bed had been on stream forapproximately 12 hours and which contained secondary and tertiarychlorides in an amount reported as 0.07 weight per cent chlorinehydrolized. Because pressure equipment was not available for thishydrolysis step a relatively low temperature of 190 F. was used and theproduct was hydrolized for 18 hours with an aqueous caustic solution ofwei ht per cent strength. The improvement obtained in treating thissample is shown by the fact that the material charged to the bauxitetreater, having 0.226 per cent chlorine had a leaded research octanenumber (Octane by Research Method; Test D-900; ASTM Manual of EngineTest Methods for Rating Fuels, March, 1948) of 91.6 and a leaded 3--Crating (Rich Mixture Rating; Test 13 -909; ASTM Manual of Engine TestMethods for Rating Fuels, March, 1948) or" "57; the condensed effluentfrom the bauxite treater having a chlorine percentage of 0.0? had aleaded research octane number of 90.6 and a leaded 3-0 rating of 60;while the hydrocarbons withdrawn from the hydrolysis step with 0.02weight per cent chlorine present had a leaded research octane number of91.9 and a leaded 3-0 rating of 82.

in order to show the advantage of the method of the present inventioninvolving the combination of bauxite treatment followed by hydrolysis,the unsatisfactory results obtained when using hydrolysis alone areshown in the following example:

l Example II A total ethylene alkylate, resulting from the alkylation ofisobutane with ethylene employing aluminum chloride catalyst, wascontaminated with primary chlorides, reported upon analysis as 0.0459weight per cent chlorine. This mixture was hydrolyzed for 3 hours at 320F. with aqueous caustic solution or 5 weight per cent strength. It wasfound that the treated mater al still contained 0.0437 weight per centof chlorine.

It is seen'that under relatively severe hydrolysis conditions in ExampleII, the amount of original primary chlorides present in the alkylatecould be reduced by only about 5% of the amount originally present. InExample I it was shown that the amount of secondary and tertiarychlorides present in the alkylate after passage over bauxite could bereduced by a relatively mild hydrolysis from 0.07 to 0.02 weight percent or by about 71 of the amount present.

In explanation of the advantages resu from the method of the presentcase, it is emphasized that when passing the through the bauxite bed,the secondary and our tiary allryl chlorides which are discharged thehydrocarbons from the bed after the bed has been in use for severalhours after its latest regeneration step are more detrimental to theoctane number and particularly to the rich r ture rating, than are theprimary allzyl ChlOllLL-ES originally present in the charge stoelz.Thus, Example I the material withdrawn from bauxite bed hadapproximately the chlorine content of the orig'nal feed stock, yet its1e; research octane number was 90.6, and its le- 3-C rating was 60,whereas the original feed spot: had a leaded research octane number of91.6 and a leaded 3-C rating or 7?. It is for 1$ ;:='Jl1 that theeilluent removed from contact with the bauxite bed is unsuitable forinclusion in motor gasoline, and particularly one itable for inclusionin aviation gasoline, if the bed n on stream as much as about 6 to 8hours aft. its previous regeneration. Even though the allzyl chloridecontent of the eiiluent is much lower than that of the charge stock, thealkyl chlorides are secondary or tertiary rather than primary and so aremuch more detrimental to the loaded octane number and 3-02 rating of theproduct.

Having fully described and illustrated preferred methods for performingthe present invention, what we desire to claim as new and useful and tosecure by Letters Patent is:

i. A method for treating a mixture con 5 of hydrocarbons in the gasolineboiling r ng contaminated with a small amount of primary alkyl chloridecapable of being converted to secondary and tertiary allryl chloridesand boiling in the same range as the hydrocarbons which includes thesteps of vaporizing the mixture and contacting the vaporized mixturewith bauxite at a temperature within the range of 500 to 900 F. at apressure of 70 p. s. i. g. for a time from 0.01 to 1 second to convertsubstantially all of said primary alkyl chloride therein at leastportion of said primary alkyl chloride being converted to secondary andtertiary allryl chlor' l-anx.

e. and removing as an effluent from contact wit the bauxite thevaporized hydrocarbon contarrinated with secondary and tertiary alkylchlorides and substantially no primary alkyl chlorides, condensing theeffluent and contacting the condensed effluent with aqueous causticsolution in a hydrolysis step at a temperature within the range of about180 to 500 F. for a time suflicient to hydrolyze substantially all ofsaid secondary and tertiary alkyl chlorides, and then separatelyremoving a hydrocarbon fraction substantially free of alkyl chloridesfrom said hydrolysis step.

2. A method in accordance with claim 1 in which the mixture treated is a01+ fraction resulting from the distillation of product obtained byalkylating isoparaffins with a low boiling olefin in the presence of analuminum halide catalyst.

3. A method for treating a hydrocarbon mixture containing 07+hydrocarbons contaminated with a small amount of primary alkyl chloridecapable of being converted to secondary and tertiary alkyl chloridesboiling in the same range as the hydrocarbons which includes the stepsof vaporizing the mixture and contacting the mix ture with a bed ofbauxite at 700 F. at a pressure of 70 p. s. i. g. for 0.1 second toconvert substantially all of said primary alkyl chloride containedtherein, at least a portion of said primary alkyl chloride beingconverted to secondary and tertiary alkyl chlorides, and removing as anefiluent from contact with the bed of bauxite vaporized hydrocarboncontaminated with secondary and tertiary alkyl chlorides andsubstantially no primary alkyl chlorides, condensing the eflluent andcontacting the condensed efiiuent with aque ous caustic solution of 5Weight per cent strength in a hydrolysis step at F. for 18 hours tohydrolyze substantially all of said secondary and tertiary alkylchlorides, and recovering a hydrocarbon fraction from said hydrolysisstep sub stantially free of alkyl chlorides.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,984,725 Britton et a1 Dec. 18, 1934 2,110,838 Britten et a1.May 8, 1938 2,315,871 Oberfell et a1. Apr. 6, 1943 2,410,498 Hepp Nov.5, 1946 2,435,621 Brooks et al. Feb. 10, 1948 2,463,930 Wildrnan Mar. 8,1949 OTHER REFERENCES Rec. Trav. Chim. 59, 793-810 (1940). Article bySchmit et a1., abstracted in Chemical Abstracts 35, 4728 (1941).

1. A METHOD FOR TREATING A MIXTURE CONSISTING OF HYDROCARBONS IN THEGASOLINE BOILING RANGE CONTAMINATED WITH A SMALL AMOUNT OF PRIMARY ALKYLCHLORINE CAPABLE OF BEING CONVERTED TO SECONDARY AND TERTIARY ALKYLCHLORIDES AND BOILING IN THE SAME RANGE AS THE HYDROCARBONS WHICHINCLUDES THE STEPS OF VAPORIZING THE MIXTURE AND CONTACTING THEVAPORIZED MIXTURE WITH BAUXITE AT A TEMPERATURE WITHIN THE RANGE OF 500*TO 900* F. AT A PRESSURE OF 70 P.S.I.G. FOR A TIME FROM 0.01 TO 1 SECONDTO CONVERT SUBSTANTIALLY ALL OF SAID PRIMARY ALKYL CHLORIDE THEREIN ATLEAST A PORTION OF SAID PRIMARY ALKYL CHLORIDE BEING CONVERTED TOSECONDARY AND TERTIARY ALKYL CHLORIDES AND REMOVING AS AN EFFLUENT FROMCONTACT WITH THE BAUXITE THE VAPORIZED HYDROCARBON CONTAMINATED WITHSECONDARY AND TERTIARY ALKYL CHLORIDES, AND SUBSTANTIALLY NO PRIMARYALKYL CHLORIDES, CONDENSING THE EFFLUENT AND CONTACTING THE CONDENSEDEFFLUENT WITH AQUEOUS CAUSTIC SOLUTION IN A HYDROLYSIS STEP AT ATEMPERATURE WITHIN THE RANGE OF ABOUT 180* TO 500* F. FOR A TIMESUFFICIENT TO HYDROLYSIS SUBSTANTIALLY ALL OF SAID SECONDARY AND TETIARYALKYL CHLORIDES, AND THEN SEPARATELY REMOVING A HYDROCARBON FRACTIONSUBSTANTIALLY FREE OF ALKYL CHLORIDES FROM SAID HYDROLYSIS STEP.